Mark-release-recapture experiments were carried out in Sabah, East Malaysia on the malaria and filariasis vector, Anopheles balabacensis. Samples of wild females were marked with different colours of fluorescent pigments, released in man-baited huts fitted with exit traps. Simultaneous collections and releases were also made in night-biting catches on a water buffalo and on four men. All subsequent recaptures were made in the same situation in which the mosquitoes were marked. The same individual mosquitoes were caught biting men and buffalo on different occasions and the numbers caught showed a strong preference for man over buffalo. The length of the oviposition cycle in the field was found to be 3.0 days. After blood-feeding on man in a hut, An. balabacensis were found to exit on the night or early morning. The same individual mosquitoes were found resting in the hut or exit trap on different occasions. The results indicate that there is strong evidence for the existence of genetic variability in the tendency of An. balabacensis to rest in houses and to bite man and buffalo. The obvious existence of this phenomenon is considered discouraging for the prospects of interruption of malaria transmitted by An. balabacensis in nature.
126 Malay children from higher income families were followed-up regularly from birth to six years of age in the University Hospital, Kuala Lumpur. Their developmental performance was compared to that of Denver children. Generally, Malaysian and Denver children appear to be similar in their development during the first six years of life except for some minor differences in the personal-social, language and gross motor sectors. Malaysians appear to be slower in self-care but more advanced in "helping around the house", "playing interactive games" and in "separating from mother". They were slightly slower in gross motor function during the first year of life but more advanced during the second year of life. However, they were slightly more advanced in language development. The differences in development between the two groups of children are discussed and it is concluded that the differences can partly be explained by differences in socio-economic or cultural differences between the two groups of children. However, the influence of genetic factors cannot be dismissed.